How to configure mouse, touchpad, other evdev devices without X11 under wayland?
 

For now I use a file in xorg.con.d to configure my mouse for example:

Section "InputClass"
Identifier "Mouse"
MatchIsPointer "yes"
Option "AccelerationProfile" "-1"
Option "AccelerationScheme" "none"
EndSection

or:

Section "InputClass"
Identifier "evdev pointer catchall"
MatchIsPointer "on"
MatchDevicePath "/dev/input/event*"
Driver "evdev"
Option "Sensitivity" "1.0"
Option "Resolution" "400"
EndSection

The only other way I know of configuring the mouse is either through xset (which is broken) or xinput (which has none of the above options for my mouse).

The synaptics driver is a bit better with the use of synclient, although there are many options that you cannot configure through it as well.

Then of course there is the nvidia driver which has many options under X with no other way of setting them as far as I know.

I'm sure there are many other devices with settings too that I'm not using at the moment. How would I configure these the same way without X?

this is how it is done .
https://wiki.gnome.org/Wayland/gnome-settings-daemon

What if you don't use gnome? Or what if you don't use a desktop environment at all?

As far as I understand it, input events and input configuration is handled by the compositor that is used, so how you set up your mouse/keyboard depends on environment you use.